Discussion in '2-Stroke Engines' started by canalcat, Apr 4, 2015.

  1. canalcat

    canalcat Member

    How do I determine the size of my motor ? I have no said markings or stickers that I can see!

  2. dougsr.874

    dougsr.874 Active Member

    Size of the piston
  3. wheelbender6

    wheelbender6 Well-Known Member

    It's stamped on the cylinder of most engines. China girl 2 strokes do not have engine displacement
    shown on them anywhere. The China girls are 50 or 66cc.
  4. jaguar

    jaguar Well-Known Member

    measure the inner cylinder diameter. 40mm is a 48cc
  5. HeadSmess

    HeadSmess Well-Known Member

    look at pics. once learnt, the difference is obvious. 66 usually have slant heads (not always) and the cylinder seems more "vertical" on the case. theres more but those features stick out as obvious...

    or yeah..40mm= 50cc, 47mm = 66cc (piston diameters)
  6. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    If it has 8 mm head studs it is a 47 mm bore 66 cc or 69 cc

    If it has 6 mm head studs it is probably a 48 cc with a 40 mm bore.
    The 48 cc sizes are not as common as the 66 cc motors.

    The studs are also further apart on a 66cc than a 48 cc

    What did your seller say it was?
    There is no such engine size as a 80.

    There are 2 kinds of 47 mm bore 66 cc pistons, one has a lower wrist pin
    hole location than the other.
    They both use the same rings and needle bearing,
    but the wrist pin is shorter on the high hole piston.
  7. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    There is no need to remove the cylinder head to figure out what size motor you have.
  8. canalcat

    canalcat Member

    My seller said its 66cc.
  9. jaguar

    jaguar Well-Known Member

    yes, the 66cc has more distance between cylinder bolts than the 48cc which is 43mm
  10. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Do you doubt it?
    8 mm head studs would prove that.